Robust zero-energy bound states in a helical lattice
Abstract
Atomic-scale helices exist as motifs for several material lattices. We examine a tight-binding model for a single one-dimensional monatomic chain with a p-orbital basis coiled into a helix. A topologically nontrivial phase emerging from this model supports a zero-energy mode localized to a boundary, always embedded within a continuum band, regardless of termination site. We identify a topological invariant for this phase that is related to the number of zero energy end modes by means of the bulk-boundary correspondence, and give strict conditions for the existence of the bound state. Another, non-topological, gapped edge mode in the model spectrum has practical consequences for surface states in e.g. trigonal tellurium and selenium and other van der Waals-bonded one-dimensional semiconductors.
Cite
@article{arxiv.1707.08064,
title = {Robust zero-energy bound states in a helical lattice},
author = {Pengke Li and Jay D. Sau and Ian Appelbaum},
journal= {arXiv preprint arXiv:1707.08064},
year = {2017}
}